Circuit-interrupter system



.Oct. 11, 1927.

J. W. LEGG CIRCUIT INTERRUPTER SYSTEM Filed Dec.

WITNESSES: 17.61%

ATTORNEY Patented Oct. 11, 1927.

UNITED STATES PATENT -oi= 1cE+ JOSEPH W. LEGG, WILKINSBURG,PENNSYLVANIA, ASSIGNOR TO WESTINGHOU SE ELECTRIC & MANUFACTURINGCOMPAHY, A CORPORATION OF PENNSYLVANIA.

- CIRC'UIT-IN'TERRUPTER SYSTEM.

Application filed December 13, 1920. Serial No. 430,155.

My invention relates to circuit-interrupting devices and particularly toelectric valves for interrupting currents of relatively high values. 7

One object of my invention is to provide an electriccircuit-interrupting valve comprising a metal casing in combination withan arc-extinguishing auxiliary circuit and means for compensating forthe inductive valve arc. Heretofore, it has been usual to employelectric valves ofgthe mercury-vapor type to interrupt circuits ofrelatively low current values. Such valves have usually employed glassbulbs'or containers which, of

themselves, added no inductance to the circuits to which they wereconnected. It is desirable, lf not imperative, in connection withcircuits carrying currents of relatively high values, to employso-called metalcase valves which have metalcontainers in lieu of glassbulbs. A -metal container introduces a very undesirable inductiveefi'ect into a circuit, when utilized as an element of an interrupter.

In practising my invention, I provide a metal-case valve connected inseriesin a main circuit to function as an interrupter therefor and alocal condenser circuit adapted to discharge acurrent in opposition tothe valve arc diverting the current from the arc path to quench thelatter and to, thereby, interrupt the main circuit.

A conductor, forming a part of the condenser circuit, is closely coupledwith the field of the valve current in order to permit a diversion ofthe current from the valve circuit to the condenser circuit withoutsubstantially ehanging the magnetic-field conditions in the surroundingspace. A re-. sistor is so related to the valve as to ermit a dischargeof the stored energy of t e circuit in order to prevent there-establishing,

of the valve are by reason of an excessive rise of voltage acrossthevalve terminals,

. Figure 1 of the accompanying drawings is a diagrammatlc view of anelectric system and an electric valve embodying my invention. j

Fig. 2. is a diagrammatic view of a usual arrangement, with anelectrical valve and a condenser connected across the terminals thereofoutside the casing, and

Fig. 3 is a simplified diagram. of the system shown in Fig. 1. V

A system embodying my invention, may comprise, in general, adirect-current generator 1, a trolley, or other supply, conductor 2 thatis connected to the generator 1 through an electric valve-3 and aconductor 4, aseries transformer 5, a relay 6, a condenser 7, a chargingresistor 8 vfor the condenser 7, a resistor 9, a circuit interrupter,10, a return-line conductor or track 11 and a load or electric vehicle12.

are connected between the positive and negathe interrupter 10, aconductor 16 and a conductor 17 to the conductor.

The valve 3 comprises a metal casing 18 that is connected to thepositive line conductor 2 by a connector 19 and is insulated from theground by insulators 20. The upper end of the casing 18 is provided witha flange 21 for the reception of a depending flange 22 of a cover. plateor member 23. The flanges 21.. j

and 22 are hermetically sealed, as by a ring 24 of wax or othermaterial. The cover 25 and a countersunk portion26to provide a shoulder27 A hollow insulating bushing 28 having an enlarged upper portion 29,displate 23 is provided with a central aperture.

posed in the countersunk portion 26, is sup- 7 ported on the shoulder 27and has a reduced end portion 30 extending through the aperture 25 intothe casing.

An anode 31 comprising a water cooled jacket 32 extends through, and issupported by, the bushing 28 in which a nut 33, supported on a shoulder34 in the bushing, and the water jacket 32 are hermetically sealed, asby a sleeve 35 of wax. The upper end of the water jacket 32constitutingthe anode3l is connected, by nuts 36 and a terminalconnector 37, to the conductor 4.

A conductor. 38, extending through the aperture 25 and having itslowerend 39 sub- The condenser? and its charging resistor 8 Y winding 45 thatmay be connected, through a spark gap 46 and a conductor 47, to theterminals of an actuating coil 48 of the relay 6. A pivoted arm 49 isadapted to be actuated, in response to energization of the relay coil48, to cause the engagement of contact members 50 that are connected, bythe conductor 17 and a flexible conductor 51, between the conductor 4and a terminal 52 of the condenser 7. I

4 2 shows the usual method of connecting a condenser across an electricvalve. With the condenser 7 connected across the outside of the valve 3,to interrupt the circuit, the collapsing magnetic flux surrounding thecurrent path, especially in the iron casing 18, will oppose the decreaseof the current in the valve, making it very difiicult to quench orinterrupt thevalve-arc.

In accordance with my invention and as shown in Figs. 1 and 3, themaincircuit ourrent and the condenser current pass through the casing 18in the same direction, as indicated by arrows 57 and 58, respectively.In

this case the flux induced by the current in y N the valve path 31,40 issubstantially identical with the flux induced bythe currentin A theconductor38 of the condenser circuit and the transfer of the currentfrom the valve path to the condenser circuit takes place readily withthe magnetic-flux conditions remaining practically unchanged. \Vith suchorganization a relatively small condenser is sufiicient to quench thevalve arc.

In operation, by reason of the spark gap I 46 in the relay-circuit,ordinary load fluctua'- tions will not affect the system. In response toa predetermined rate of change of load current, or in response to ashort circuit across the generator, a spark will jump the gap 46 toenergize the relay coil 48. This action will operate the rela'yarm 49 toclose the contact member 50, whereupon, the con denser circuit will beconnected in parallel to the valve-arc path between the positive lineconductor 4 and the mercury cathode 40. The condenser discharges 1nopposition to the arc current, diverting the line current from the arcpath to the condenser conduc-' tor 38, such action not being opposed bythe surrounding magnetic field, as explained above. The diversion of theline current to:

the condenser circuit will interrupt the main circuit connection throughthe mercury-arc valve, leaving only an auxiliary discharge resistor 9connected in parallel to the valve to permit a discharge of the storedenergy of the circuit. Therelatively slow-acting interrupter 10 will nowoperate to fully clear the main circuit by opening the circuit throughthe shunting resistor 9.

The shunting resistor 9, however, remains connected in parallel to thevalve gap for a sufiicient time after the operation of the sensitiverelay 6 to provide a discharge path for the current induced by the fieldsurrounding the current paths within the valve when the field finallycollapses, after the condenser has finally stopped the current flow inthe line, thus preventing the development of high voltages and thedanger of arc-reignition.

The arrangement whereby the resistor 9 prevents high-voltagesurgesacross the valve and whereby the conductor 38 conducts the condensercurrent through the casing 18 in the same direction in which themain-circuit sition as to require the condenser to be of only suflicientcapacity to overcome the potential drop across the valve to permanentlyopen the main circuit.

While I- have shown and described a particular form of 'my invention, itis equally applicable in connection with other devices where the fieldinterlinked with the interrupting circuithinders the interruption of thecurrent.

I claim as my invention 1. A circuit-interrupting system comprising acircuit, anelectric valve disposed therein and-having inductivecharacteristics,

means for momentarily diverting the current from the valve to extinguishthe valve "arc,means for reducing the inductive effect I of the valveduring the interruption of the current therethrough and means forreducing inductive effects of the valve during .the interruption of thecurrent in the circuit. 2. A-metal-case electric valve havingmaincircuit terminals, a condenser having its circuit connected to dischargeacross the valve, 'isaid condenser'circuit being so related to theLeasing that the decrease'of the valve current does not substantiallychange the magnetic flux conditions 'in the surrounding space, and meansfor preventing a surge of induced current upon the interruption of thecurrent through the main circuit.

body of mercury therein constituting the '3. The combination withanelectr-ic valve I cathode thereof, circuit and terminals conconductorleading in said casing parallel'to 'thedischarge path between said anodeand nected to the anode and to the cathode, of a said cathode, a 1condenser-means. connected ductor between said cathode and said anode.

4.: The combination with an electric. valve comprising a metal casing,an insulating bushing in a wallsthereof, anfanode extend ing into thecasing through the bushing,

and a mercury cathode in the casing, of 3-.

conducting member surrounding the bushlng and insulated fromsaidcaslng', said member having a portionextendingto the cathode, acondenser,and means for connecting said condenser between the anode andsaid conducting member.

5. An electrical device comprising a mag;

netizable wall portion, a main circuitv terminal member extendingthroughsaid wall "portion and insulated therefrom, an-auxiliary terminal memberextending through said wall portion adjacentto said main circuitterminal member and insulated from both said wall portion and said maincircuit terminal member, a means for discharging a current through saidauxiliary terminal member to momentarily divertthe normal current flowfrom said main circuit terminal member, said means being so connectedthat the current discharge does not substantially affect the magneticflux inter linked with said terminal members.

6. An electrical device comprising a magnetizable wall portion, a maincircuit terminal member extending through said wall portion andinsulated therefrom, an auxiliary terminal member extending through saidwall portion adjacent to said main circuit terminal member and insulatedfrom both said wall portion and said main circuit terminal member, acondenser means for discharging a current through said auxiliaryterminal member to momentarily divert the normal current flow from saidmain circuit terminal member, said condenser means being so connectedthatthe current discharge does not substantially affect the magneticflux interlinked with said terminal members.

7. An electric valve having a pair of main terminal members, the flow ofcurrent throught said main terminal members inducing an appreciablemagnetic flux in the surrounding space, an auxiliary terminal memberadjacent to one of said main terminal members, a condenser means fordischarging a current through said auxiliary terminal member tomomentarily divert the current from the adjacent main terminal memberand interrupt the valve circuit, said condenser means being soconnectedthat the interruption of the current in the valve circuit does notsubstantially aifect the magnetic flux conditions in the surroundingspace.

8. A mercury-arc electric valve having a pair of discharge terminals,the flpw of current through said disohargeter ninalsin:

ducing an appreciable magnetic flux in the.

surrounding space, an auxiliary terminal member adjacent to one of saiddischarge terminals, a condenser means for discharging a current throughsaid auxiliary terminal member and the other of saidcdischargeterminalsto momentarily divert the currentfrom said one of said dischargeterminals andinterrupt the valve circuit, said condenser means being soconnected that the interruptionof the current in the valve circuit doesnot substantially affect the mag netic flux conditions-in the surroundng space.

a circuit interrupter, a casing therefor having amagnetizable Wallportion, a pair of oppos tely disposed main terminal members for saidcircuitinterrupter, at leastone of said main terminal members extend ngthrough said wall portion and insulated therefrom, the flow of currentthrough said main terminal members inducing an appreciable magnetic fluxin said magnetizable wall portion, an auxiliary terminal memberextending through said magnetizable wall portion adjacent to said one ofsaid main terminal members, said auxiliary terminal memberbeingconnected, inside said casing, to the other of the main terminalmembers, an external circuit including a condenser connected to saidauxiliary terminal member, means for causing the current to beinterrupted in said circuit interrupter and momentarily transferred tosaid condenser circuit whereby the magnetic flux conditions in saidcasing are substantially unaltered during the interruption of saidcircuit-interrupter current, and means for providing a discharge pathfor the current induced by the change in the magnetic flux conditionssubsequently to the transfer of the current to said condenser circuit.

10. An electric-discharge valve having a pair of discharge electrodes, acondenser, means for discharging said condenser through the path betweensaid electrodes to interrupt a discharge therethrough, an auxiliarydischarge path connected in shunt to said electrodes, and meansresponsive to the interruption of the circuit through said valve foropening the circuit through said auxiliary discharge path.

11. An electric-discharge valve having a pair of discharge electrodes, acondenser, means for discharging said condenser through the path betweensaid electrodes to interrupt a discharge therethrough, a resistorconnected in shunt to said electrodes, and means responsive to theinterruption of the circuit through said valve for opening the circuitthrough said resistor.

12. A mercury-arc Valve comprising a metallic envelope, a mercurycathode, an

9. The combination with ,a power line, of.

anode, an auxiliary conductor disposed in said casing parallel to thedischarge path between said cathode and said anode, and means fordiverting the current from the discharge path to said conductor.

13. A space-current discharge device of a type adapted to sustain itsdischarge by the passage of the space current itself, said devicecomprising a magnetizable metallic casing, an anode and a cathode, mainterminals for said anode and said cathode, respec tively, an auxiliaryterminal adjacent to one of said main terminals, an auxiliary conductorinside said casing connecting said auxiliary terminal with the othermain terminal inside said casing, and external circuit connections fordiverting the main current to the auxiliary terminal and the auxiliaryconductor from the adjacent main terminal and'the space-currentdischarge path within the casing.

14. A space-current discharge device of a type adapted to sustain itsdischarge by the passage of the space-current itself, said devicecomprising a magnetizable metallic casing, an anode and a cathode, mainterminals for said anode and said cathode, respectively, an auxiliaryterminal adjacent to one of said main terminals, an auxiliary conductorinside said casing, connecting said auxiliary terminal'with the othermain terminal inside said casing, and external circuit connections forconnecting a condenser between said auxiliary terminal and the adjacentmain terminal, said condenser drawing a sufiiciently large chargingcurrent to divert themain current from the space -current discharge pathwithin the casing.

In testimony whereof, I have hereunto subscribed my name this 8rd day ofDecember, 1920.

JOSEPH W. LEGG.

